The insects of the world have many ways to communicate with one another. Among them are color, scent, sound…and light. Several groups of insects glow, but only one—fireflies—has evolved an extraordinary language of light.
Many fireflies—actually not flies at all, but beetles—use a system of flashes in some of the same ways we use words: to attract attention, to identify one another, and even to deceive. Scientists have studied the “Morse code” of various species to learn more about their behavior.
Finding the right mate is behind most firefly flickering. Unique blinking patterns let males and females of the same species recognize one another in the dark. The brighter, faster, flashier male signals act like catnip to females, who return precisely timed blinks if they like what they see.
But the light is about more than looking for love. Communicating with light has a dark side—predators can see it, too. Some species use their glow to discourage predators by signaling that the insect they are about to eat will taste very, very bad.
Even stranger, females of several species in the firefly genus Photuris flash the signals of other firefly species to lure foreign males to their deaths. These femme fatales aren’t after a mate—they’re after a meal!